A substrate is applied to a variety of products, for example, a flat display device such as a Liquid Crystal Device (LCD) or a Plasma Display Device (PDP).
The substrate, which is used in a variety of devices such as the above, is a final product resulting from a variety of semiconductor processes, and is carried by feed rollers so that it can be subjected to respective semiconductor processes.
An example of the feed rollers are feed rollers that carry the substrate, which include upper and lower rows of feed rollers, and which are configured such that they can rotate while facing each other. The shaft of the upper feed roller and the shaft of the lower feed roller are connected to each other such that they can be simultaneously driven and rotated, so that the substrate can be carried therebetween.
Each of the upper and lower feed rollers is provided with an O-ring made of a rubber material and a resin material. The O-ring prevents slipping by providing a frictional force when the substrate is carried so that the substrate can be properly carried without being damaged.
The O-ring has the form of a closed loop, and each feed roller is provided with a plurality of such O-rings, which are coupled to the feed roller at regular intervals. Since the O-rings, which are disposed like above, serve to repeatedly carry substrates for a long time, they become worn because of their contact with the substrates and come to have irregular sizes. In addition, since contact and abrasion decrease the frictional force, it becomes difficult to properly carry the substrates.
Therefore, an O-ring must be replaced with a new one after it has been used for a predetermined time or becomes damaged.
However, since the above-described O-ring of the related art is in the form of a closed loop, cumbersome operations are required in order to assemble a new O-ring to the feed roller. Specifically, various devices and components connected to one shaft of the feed roller need to be disassembled therefrom, and the new O-ring is assembled to the separated feed roller by fitting it through one end of the feed roller. Consequently, the replacement of an existing O-ring with a new one takes a long time, and the operation is inefficient because of cumbersomeness. In addition, during the replacement operation, the conveyor system must be stopped and the production of substrates is stopped. This, consequently, becomes a cause of a decrease in productivity.
In addition, there are inconveniences in that the disassembled components and devices must be re-fastened to be reassembled, and the coupling position and fastened state of the upper and lower feed rollers are checked and set again, after the O-ring has been replaced.
Furthermore, the O-ring used in the feed roller may have a circular or non-circular (e.g., quadrangular) cross-section, and an O-ring fastening recess (e.g., an annular recess) is formed such that it corresponds to the cross-section of the O-ring used in the feed roller. Therefore, there is a problem in that, in the event of replacing an existing O-ring with a new one, only an O-ring having a shape corresponding to the O-ring fastening recess formed in the feed roller can be used. For example, an O-ring having a circular cross-section only has a small area that is in contact with the substrate. In contrast, a large area of an O-ring having a non-circular cross-section (e.g. a quadrangular cross-section) makes contact with the substrate, thereby conveying the substrate more stably. Accordingly, there is a problem in that the feed roller must be replaced with a new one when replacing an existing O-ring having a circular cross-section with an O-ring having a non-circular cross-section.